browser_performance_metrics

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full disclosure burden. It usefully signals that this is a passive read ('Retrieve') of a point-in-time snapshot ('real-time'), which implies no side effects, and it names the units for heap memory. It does not state whether a page/tab must be active, whether values are cumulative since load, or how often they refresh.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence: verb, resource, then the enumerated return fields. Zero filler, no redundancy, and the most important information leads.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Because there is no output schema, the description must convey what comes back, and it does list the four returned metrics with units for heap. For a zero-parameter, side-effect-free read tool this is nearly complete, though it omits the unit/semantics of 'task duration' and DOM node/layout counts.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there are no argument semantics to document and the baseline is 4. The description does not need to compensate for any schema gap here.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The definition gives a specific verb ('Retrieve') plus a clearly scoped resource ('real-time browser performance metrics') and enumerates exactly which metrics are returned (JS heap MB, DOM node count, layout count, task duration). This cleanly separates it from neighbors like browser_network_requests or browser_console_logs. It does not explicitly name a sibling it should be preferred over, which keeps it from a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no guidance on when to reach for this tool versus related diagnostics such as browser_network_requests, browser_console_logs, or browser_system_info. Usage is only faintly implied by the metric names; no prerequisites (e.g. a page must be loaded) or exclusions are stated.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.